The Stellar Halos of Massive Elliptical Galaxies. Ii. Detailed Abundance Ratios at Large Radius

Greene, Jenny E.; Murphy, J.H.; Graves, Genevieve J.; Gunn, James E.; Raskutti, Sudhir; Comerford, Julia M.; Gebhardt, Karl

doi:10.1088/0004-637x/776/2/64

Cited by 92 publications

(143 citation statements)

References 150 publications

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“…9 and 18). These results are in contrast with recent results by Greene et al (2012Greene et al ( , 2013: for a sample of ∼30 early type galaxies they find at 2 R eff an old (10 Gyr) stellar population with [Fe/H] ∼ −0.5, and interpret this as the stellar outskirts of these galaxies being built up through minor mergers. Coccato et al (2010), La Barbera et al (2012), Montes et al (2014) observing a few massive ellipticals reported a decline of the metallicity to under solar in an old stellar population in their outskirts (≥10 R eff ) suggesting that these galaxies are formed in two phases, the central core through major mergers, and through minor mergers farther out.…”

Section: Implications From This Work and Comparisoncontrasting

confidence: 99%

“…Coccato et al (2010), La Barbera et al (2012), Montes et al (2014) observing a few massive ellipticals reported a decline of the metallicity to under solar in an old stellar population in their outskirts (≥10 R eff ) suggesting that these galaxies are formed in two phases, the central core through major mergers, and through minor mergers farther out. However, other recent works show examples of ETG with an old and metal-rich stellar population and a very shallow metallicity gradient up to 3 R eff in contrast with the results by Greene et al (2012Greene et al ( , 2013.…”

Section: Implications From This Work and Comparisoncontrasting

confidence: 82%

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The CALIFA survey across the Hubble sequence

Delgado

García-Benito

Pérez

et al. 2015

A&A

234

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Various different physical processes contribute to the star formation and stellar mass assembly histories of galaxies. One important approach to understanding the significance of these different processes on galaxy evolution is the study of the stellar population content of today's galaxies in a spatially resolved manner. The aim of this paper is to characterize in detail the radial structure of stellar population properties of galaxies in the nearby universe, based on a uniquely large galaxy sample, considering the quality and coverage of the data. The sample under study was drawn from the CALIFA survey and contains 300 galaxies observed with integral field spectroscopy. These cover a wide range of Hubble types, from spheroids to spiral galaxies, while stellar masses range from M ∼ 10 9 to 7 × 10 11 M . We apply the fossil record method based on spectral synthesis techniques to recover the following physical properties for each spatial resolution element in our target galaxies: the stellar mass surface density (µ ), stellar extinction (A V ), light-weighted and mass-weighted ages ( log age L , log age M ), and mass-weighted metallicity ( log Z M ). To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd). We confirm that more massive galaxies are more compact, older, more metal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M , which is evidence that quenching is related to morphology, but not driven by mass. Negative gradients of log age L are consistent with an inside-out growth of galaxies, with the largest log age L gradients in Sb-Sbc galaxies. Further, the mean stellar ages of disks and bulges are correlated and with disks covering a wider range of ages, and late-type spirals hosting younger disks. However, age gradients are only mildly negative or flat beyond R ∼ 2 HLR (half light radius), indicating that star formation is more uniformly distributed or that stellar migration is important at these distances. The gradients in stellar mass surface density depend mostly on stellar mass, in the sense that more massive galaxies are more centrally concentrated. Whatever sets the concentration indices of galaxies obviously depends less on quenching/morphology than on the depth of the potential well. There is a secondary correlation in the sense that at the same M early-type galaxies have steeper gradients. The µ gradients outside 1 HLR show no dependence on Hubble type. We find mildly negative log Z M gradients, which are shallower than predicted from models of galaxy evolution in isolation. In general, metallicity gradients depend on stellar mass, and less on morphology, hinting that metallicity is affected by both -the depth of the potential well and morphology/quenching....

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Section: Implications From This Work and Comparisoncontrasting

confidence: 99%

Section: Implications From This Work and Comparisoncontrasting

confidence: 82%

The CALIFA survey across the Hubble sequence

Delgado

García-Benito

Pérez

et al. 2015

A&A

234

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“…In the following, we will mainly compare the observational results of Coccato et al (2010); La Barbera et al (2012); Greene et al (2012Greene et al ( , 2013Pastorello et al (2014);D'Souza et al (2014) and Raskutti et al (2014) for ellipticals to our simulations, even if most of these studies do not measure gradients significantly beyond 3 R eff (expect of La Barbera et al 2012). Therefore, we want to emphasize that our simulations provide predictions of outer gradients for future, more elaborate observational surveys which will (hopefully) strengthen our (preliminary) conclusions below.…”

Section: Comparison With Observationsmentioning

confidence: 69%

The stellar accretion origin of stellar population gradients in massive galaxies at large radii

Hirschmann

Naab

Ostriker

et al. 2015

Monthly Notices of the Royal Astronomical Society

100

155

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We investigate the evolution of stellar population gradients from z = 2 to z = 0 in massive galaxies at large radii (r > 2R eff ) using ten cosmological zoom simulations of halos with 6 × 10 12 M ⊙ < M halo < 2 × 10 13 M ⊙ . The simulations follow metal cooling and enrichment from SNII, SNIa and AGB winds. We explore the differential impact of an empirical model for galactic winds that reproduces the mass-metallicity relation and its evolution with redshift. At larger radii the galaxies, for both models, become more dominated by stars accreted from satellite galaxies in major and minor mergers. In the wind model, fewer stars are accreted, but they are significantly more metal poor resulting in steep global metallicity ( ∇Z stars = −0.35 dex/dex) and color (e.g. ∇g − r = −0.13 dex/dex) gradients in agreement with observations. In contrast, colour and metallicity gradients of the models without winds are inconsistent with observations. Age gradients are in general mildly positive at z = 0 ( ∇Age stars = 0.04 dex/dex) with significant differences between the models at higher redshift. We demonstrate that for the wind model, stellar accretion is steepening existing in-situ metallicity gradients by about 0.2 dex by the present day and helps to match observed gradients of massive early-type galaxies at large radii. Colour and metallicity gradients are significantly steeper for systems which have accreted stars in minor mergers, while galaxies with major mergers have relatively flat gradients, confirming previous results. The effect of stellar migration of in-situ formed stars to large radii is discussed. This study highlights the importance of stellar accretion for stellar population properties of massive galaxies at large radii, which can provide important constraints for formation models.

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“…To date, we have IFU spectroscopy for 70 of the 116 galaxies in the MASSIVE survey. With these data we are measuring stellar population gradients (Greene et al 2013(Greene et al , 2015, molecular gas masses and star formation efficiencies (Davis et al 2016), stellar kinematic fields (M. Veale et al 2016, in preparation), and, when combined with modeling, the enclosed dark matter halo mass (e.g., Thomas et al 2011). …”

Section: The Massive Surveymentioning

confidence: 99%

The Massive Survey. Iv. The X-Ray Halos of the Most Massive Early-Type Galaxies in the Nearby Universe

Goulding

Greene

et al. 2016

ApJ

Self Cite

112

156

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Studies of the physical properties of local elliptical galaxies are shedding new light on galaxy formation. Here we present the hot-gas properties of 33 early-type systems within the MASSIVE galaxy survey that have archival Chandra X-ray observations, and we use these data to derive X-ray luminosities (L X,gas ) and plasma temperatures (T gas ) for the diffuse gas components. We combine this with the ATLAS 3D survey to investigate the X-ray-optical properties of a statistically significant sample of early-type galaxies across a wide range of environments. When X-ray measurements are performed consistently in apertures set by the galaxy stellar content, we deduce that all early types (independent of galaxy mass, environment, and rotational support) follow a universal scaling law such that µL T X,gas gas 4.5 . We further demonstrate that the scatter in L X,gas around both K-band luminosity (L K ) and the galaxy stellar velocity dispersion (s e ) is primarily driven by T gas , with no clear trends with halo mass, radio power, or angular momentum of the stars. It is not trivial to tie the gas origin directly to either stellar mass or galaxy potential. Indeed, our data require a steeper relation between L L , K X,gas , and s e than predicted by standard mass-loss models. Finally, we find that T gas is set by the galaxy potential inside the optical effective radius. We conclude that within the innermost 10-30 kpc region, early types maintain pressure-supported hot gas, with a minimum T gas set by the virial temperature, but the majority show evidence for additional heating.

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The Stellar Halos of Massive Elliptical Galaxies. Ii. Detailed Abundance Ratios at Large Radius

Cited by 92 publications

References 150 publications

The CALIFA survey across the Hubble sequence

The CALIFA survey across the Hubble sequence

The stellar accretion origin of stellar population gradients in massive galaxies at large radii

The Massive Survey. Iv. The X-Ray Halos of the Most Massive Early-Type Galaxies in the Nearby Universe

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